Two is a company, three is a crowd; every other person except your spouse is a third party. God is the only third party in marriage that makes it work. Let Him in!
“Two are better than one; because they have a good reward for their labour. For if they fall, the one will lift up his fellow: but woe to him that is alone when he falleth; for he hath not another to help him up. Again, if two lie together, then they have heat: but how can one be warm alone? And if one prevail against him, two shall withstand him; and a threefold cord is not quickly broken.” – Ecclesiastes 4: 9-12